Shielded Labs, led by Zcash founder Zooko, has received a second donation from Ethereum co-founder Vitalik Buterin to support its Crosslink project. Crosslink aims to improve Zcash’s PoW consensus by adding a parallel finality layer to prevent chain reorganizations and rollback attacks. Shielded Labs operates independently from Zcash’s developer fund and relies on donations from the community and supporters.